Light emitting device

ABSTRACT

The invention provides a light emitting device which is capable of displaying on both sides, has a small volume, and is capable of being used as a module. A light emitting element represented by an EL element and the like is used in a pixel portion, and two pixel portions are provided in one light emitting device. A first pixel portion has a structure to emit light only from a counter electrode side of the light emitting element. A second pixel portion has a structure to emit light only from a pixel electrode side of the light emitting element. That is, in the first pixel portion and the second pixel portion, directions of light emission are reverse in front and back.

TECHNICAL FIELD

[0001] The invention relates to a light emitting device provided with alight emitting element. In particular, the invention relates to aportable information terminal such as a portable phone and a PDA(Personal Digital Assistance) provided with such a light emittingdevice.

BACKGROUND ART

[0002] In recent years, a light emitting device using a light emittingelement represented by an electroluminescent (EL) element and the likehas been developed in substitution for a liquid crystal display (LCD)comprising a pixel using a liquid crystal element as a light emittingelement. These light emitting devices are expected to be widely used asa display of a portable phone and a display device by taking advantagesof high image quality, wide viewing angle, thin design without a need ofbacklight, lightweight and the like due to a light emission type.

[0003] Furthermore, a portable information terminal is demanded to havea high-value added because of the diversification of applications and isrecently provided with a sub-display on the back of a normal display.

DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In a portable information terminal provided with a sub-display inaddition to the original display, the volume occupied by a moduleincluding a backlight and the like as well as the volume occupied by asubstrate and the like mounting a control IC and the like for drivingthe aforementioned module are to be paid attention to. In particular, aportable information terminal provided recently is becoming thinner,lighter, and smaller, which is in the relation of trade-off with theadded high-value.

[0005] The invention is made in view of the aforementioned problems andprovides a light emitting device which is capable of displaying on bothsides, has a small volume, and is capable of being used as a module.

MEANS FOR SOLVING THE PROBLEM

[0006] Following measures are taken in the invention to solve theaforementioned problems.

[0007] A light emitting element represented by an EL element and thelike is used in a pixel portion and two pixel portions are provided atdifferent dispositions in one light emitting device. A first pixelportion has a structure to emit light only from a counter electrode sideof the light emitting element. A second pixel portion has a structure toemit light only from a pixel electrode side of the light emittingelement. That is, in the first pixel portion and the second pixelportion, directions of light emission are reverse in front and back.

[0008] A user normally does not look at the both sides at the same time,therefore, the display may be selected according to the application. Forexample, such a structure may be employed that a switching element isprovided in any of current paths for supplying current to the lightemitting element in order to block a current supply to the second pixelportion when utilizing the light emission of the first pixel portion,while in order to block a current supply to the first pixel portion whenutilizing the light emission of the second pixel portion. In that case,in a light emitting device comprising a first driving portion foroperating the first pixel portion, a second driving portion foroperating the second pixel portion, and a wiring for supplying a signaland a voltage to each of the first driving portion and the seconddriving portion, such a structure that a part or all of the wirings forsupplying a signal and a voltage to the first driving portion and thesecond driving portion is shared and a means for operating either of thefirst pixel portion or the second pixel portion is provided and changedover externally.

[0009] A structure of the invention is described below.

[0010] The light emitting device of the invention comprises a firstpixel portion in which a plurality of first pixels are arranged inmatrix on a panel substrate and a second pixel portion in which aplurality of second pixels are arranged in matrix on the panel substrateat a different disposition than the first pixel portion. The first pixelportion comprises the plurality of first pixels comprising first lightemitting elements which emit light from a surface of the panel substratein a direction from the back of the panel substrate to the surface ofthe substrate, and the second pixel portion comprises the plurality ofsecond pixels comprising second light emitting elements which emit lightfrom the back of the panel substrate in a direction from the surface ofthe panel substrate to the back of the panel substrate.

[0011] In the light emitting device of the invention, the first lightemitting element comprises a first pixel electrode, a firstelectroluminescent layer, and a first counter electrode. The first pixelportion emits light from the first counter electrode side, the secondlight emitting element comprises a second pixel electrode, a secondelectroluminescent layer, and a second counter electrode, and the secondpixel portion emits light from the second pixel electrode side.

[0012] In the light emitting device of the invention, directions oflight emitted from the first light emitting element and the second lightemitting element are determined depending upon the presence or absenceof a reflecting film.

[0013] In the light emitting device of the invention, the first drivingportion for operating the first pixel portion, the second drivingportion for operating the second pixel portion, and a part or all of thewirings for supplying a signal and a voltage to each of the firstdriving portion and the second driving portion is shared, and a meansfor operating either of the first pixel portion or the second pixelportion is provided.

[0014] In the light emitting device of the invention, the light emittingdevice is used in an electronic apparatus.

EFFECT OF THE INVENTION

[0015] According to the aforementioned structure of the invention, alight emitting device which is thin, lightweight, and capable ofdisplaying on both sides can be provided. Further, the number of inputsignals can be reduced by changing over or sharing a signal and avoltage which are required for driving depending on a pixel portion todrive.

[0016] The invention can be applied not only to a light emitting deviceusing an electroluminescent element as a light emitting element, butalso to other light emitting devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 are cross sectional views showing structures of a pixelportion of the light emitting device in Embodiment Mode 1.

[0018]FIG. 2 are cross sectional views showing structures of a pixelportion of the light emitting device in Embodiment Mode 2.

[0019]FIG. 3 are cross sectional views showing structures of a pixelportion of the light emitting device in Embodiment Mode 3.

[0020]FIG. 4 are cross sectional views showing structures of a pixelportion of the light emitting device in Embodiment Mode 4.

[0021]FIG. 5 is a circuit diagram showing a structure of a pixel portionof the light emitting device.

[0022]FIG. 6 are diagrams showing structures of a panel substrate as thelight emitting device of the invention described in Embodiment Mode 1.

[0023]FIG. 7 are views of a portable phone using a panel substrate asthe light emitting device of the invention described in Embodiment Mode1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] Embodiment Modes of the invention are described below.

EMBODIMENT MODE 1

[0025] One embodiment mode of the invention is shown in FIG. 1. FIG. 1are cross sectional views of a first pixel portion and a second pixelportion of one light emitting device provided with two pixel portions.The first pixel portion has a structure to emit light only from acounter electrode side of the light emitting element while the secondpixel portion has a structure to emit light only from a pixel electrodeside of the light emitting element. That is, in the first pixel portionand the second pixel portion, directions of light emission are reversein front and back.

[0026]FIG. 1A is a cross sectional view of one pixel in the first pixelportion and FIG. 1B is a cross sectional view of one pixel in the secondpixel portion. FIG. 5 shows a circuit diagram of one pixel in the firstpixel portion and the second pixel portion as an example.

[0027] Note that a thin film transistor (TFT) is used as a switchingelement and a driving element here, however, the invention is notlimited to this. For example, any of a MOS transistor, an organictransistor, a molecular transistor and the like may be used as well.

[0028] In FIG. 5, reference numeral 900 denotes a pixel, 901 denotes aswitching TFT, 902 denotes a driving TFT, and 903 denotes a lightemitting element. Further, a symbol A denotes an anode line, C denotes acathode line, G denotes a gate line, and S denotes a source line.

[0029] In FIG. 1A, reference numeral 1000 denotes a substrate and aregion surrounded by a dashed frame 1010 corresponds to a driving TFTwhich supplies a current to a light emitting element 1011 directly orthrough other circuit elements. The light emitting element 1011corresponds to a region in which a pixel electrode 1012, anelectroluminescent layer 1001, and a counter electrode 1002 arelaminated and emits light in a direction shown by a light emittingdirection 1014. The pixel electrode 1012 at this time is formed of areflecting film such as aluminum, therefore, the light emitting element1011 does not emit light in the opposite direction to the light emittingdirection 1014. Note that the pixel electrode 1012 may have a structurein which a transparent conductive film is laminated on a reflectingfilm. The counter electrode 1002 laminated above the electroluminescentlayer 1001 is formed of a transparent conductive film such as ITO whilea protective film 1004 is formed of a transmissive film such as a carbonnitride film. Reference numeral 1003 denotes an organic resin film.

[0030] In FIG. 1B, a region surrounded by a dashed frame 1020corresponds to a driving TFT which supplies a current to a lightemitting element 1021 directly or through other circuit elements. Thelight emitting element 1021 corresponds to a region in which a pixelelectrode 1022, the electroluminescent layer 1001, and the counterelectrode 1002 are laminated and emits light in a direction shown by alight emitting direction 1024. The pixel electrode 1022 is formed of atransparent conductive film and a film formed below the pixel electrode1022 and the substrate 1000 are formed of materials which transmitlight. Further, a reflecting film 1005 is formed on the protective film1004 and reflects light emitted from the light emitting element 1021 inthe opposite direction to the light emitting direction 1024. Referencenumeral 1003 denotes an organic resin film.

[0031] The electroluminescent layer 1001 is the same layer in FIG. 1Aand FIG. 1B, however, it may be formed of a different material. Theelectroluminescent layers may be formed of different materials in eachpixel.

[0032] The protective film 1004 is the same layer in FIG. 1A and FIG.1B, however, it may be formed of a different material.

[0033] Further, the electroluminescent layer 1001 may be formed of anyof a low molecular weight material, a high molecular weight material, ora medium molecular weight material.

[0034] After the light emitting device is completed up to the mode shownin FIG. 1, it is preferably packaged (sealed) with a protective film(laminate film, ultraviolet curing resin film and the like) which hashigh airtightness and less degasification or a translucent coveringmaterial in order not to expose it to the outside air.

EMBODIMENT MODE 2

[0035] One embodiment mode of the invention is shown in FIG. 2. FIG. 2are cross sectional views of a first pixel portion and a second pixelportion of one light emitting device provided with two pixel portions.The first pixel portion has a structure to emit light only from acounter electrode side of the light emitting element while the secondpixel portion has a structure to emit light only from a pixel electrodeside of the light emitting element. That is, in the first pixel portionand the second pixel portion, directions of light emission are reversein front and back.

[0036]FIG. 2A is a cross sectional view of one pixel in the first pixelportion and FIG. 2B is a cross sectional view of one pixel in the secondpixel portion. FIG. 5 shows a circuit diagram of one pixel in the firstpixel portion and the second pixel portion as an example.

[0037] In FIG. 5, reference numeral 900 denotes a pixel, 901 denotes aswitching TFT, 902 denotes a driving TFT, and 903 denotes a lightemitting element. Further, a symbol A denotes an anode line, C denotes acathode line, G denotes a gate line, and S denotes a source line.

[0038] In FIG. 2A, reference numeral 2000 denotes a substrate, and aregion surrounded by a dashed frame 2010 corresponds to a driving TFTwhich supplies a current to a light emitting element 2011 directly orthrough other circuit elements. The light emitting element 2011corresponds to a region in which a pixel electrode 2012, anelectroluminescent layer 2001, and a counter electrode 2013 arelaminated and emits light in a direction shown by a light emittingdirection 2014. The pixel electrode 2012 at this time is formed of areflecting film such as aluminum, therefore, the light emitting element2011 does not emit light in the opposite direction to the light emittingdirection 2014. Note that the pixel electrode 2012 may have a structurein which a transparent conductive film is laminated on a reflectingfilm. A counter electrode 2013 laminated above the electroluminescentlayer 2001 is formed of a transparent conductive film, a protective film2004 is formed of a transmissive film such as a carbon nitride film.Reference numeral 2003 denotes an organic resin film. In FIG. 2B, aregion surrounded by a dashed frame 2020 corresponds to a driving TFTwhich supplies a current to a light emitting element 2021 directly orthrough other circuit elements. The light emitting element 2021corresponds to a region in which a pixel electrode 2022, theelectroluminescent layer 2001, and a counter electrode 2023 arelaminated and emits light in a direction shown by a light emittingdirection 2024. The counter electrode 2023 is formed of a reflectingfilm such as aluminum, therefore, the light emitting element 2021 doesnot emit light in the opposite direction to the light emitting direction2024. Further, the pixel electrode 2022 is formed of a transparentconductive film and a film formed below the pixel electrode 2022 and asubstrate 2000 are formed of materials which transmit light. Referencenumeral 2003 denotes an organic resin film.

[0039] The electroluminescent layer 2001 is the same layer in FIG. 2Aand FIG. 2B, however, it may be formed of a different material. Theelectroluminescent layers may be formed of different materials in eachpixel.

[0040] The protective film 2004 is the same layer in FIG. 2A and FIG.2B, however, it may be formed of a different material.

[0041] The counter electrode 2013 and the counter electrode 2023 aredifferent layers in FIG. 2A and FIG. 2B, however, they may beelectrically connected to each other.

[0042] Further, the electroluminescent layer 2003 may be formed of anyof a low molecular weight material, a high molecular weight material, ora medium molecular weight material.

[0043] After the light emitting device is completed up to the mode shownin FIG. 2, it is preferably packaged (sealed) with a protective film(laminate film, ultraviolet curing resin film and the like) which hashigh airtightness and less degasification or a translucent coveringmaterial in order not to expose it to the outside air.

EMBODIMENT MODE 3

[0044] One embodiment mode of the invention is shown in FIG. 3. FIG. 3are cross sectional views of a first pixel portion and a second pixelportion of one light emitting device provided with two pixel portions.The first pixel portion has a structure to emit light only from acounter electrode side of the light emitting element while the secondpixel portion has a structure to emit light only from a pixel electrodeside of the light emitting element. That is, in the first pixel portionand the second pixel portion, directions of light emission are reversein front and back.

[0045]FIG. 3A is a cross sectional view of one pixel in the first pixelportion and FIG. 3B is a cross sectional view of one pixel in the secondpixel portion. FIG. 5 shows a circuit diagram of one pixel in the firstpixel portion and the second pixel portion as an example.

[0046] In FIG. 5, reference numeral 900 denotes a pixel, 901 denotes aswitching TFT, 902 denotes a driving TFT, and 903 denotes a lightemitting element. Further, a symbol A denotes an anode line, C denotes acathode line, G denotes a gate line, and S denotes a source line.

[0047] In FIG. 3A, reference numeral 3000 denotes a substrate and aregion surrounded by a dashed frame 3010 corresponds to a driving TFTwhich supplies a current to a light emitting element 3011 directly orthrough other circuit elements. The light emitting element 3011corresponds to a region in which a pixel electrode 3012, anelectroluminescent layer 3001, and a counter electrode 3002 arelaminated and emits light in a direction shown by a light emittingdirection 3014. The pixel electrode 3012 at this time is formed of areflecting film such as aluminum, therefore, the light emitting element3011 does not emit light in the opposite direction to the light emittingdirection 3014. Note that the pixel electrode 3012 may have a structurein which a transparent conductive film is laminated on a reflectingfilm. The counter electrode 3002 laminated above the electroluminescentlayer 3001 is formed of a transparent conductive film, a protective film3004 is formed of a transmissive film such as a carbon nitride film, anda color filter 3006 is formed of color resist and the like. By usingdifferent materials for the color filter 3006 in each pixel, light canbe emitted in different colors in each pixel. Reference numeral 3003denotes an organic resin film.

[0048] In FIG. 3B, a region surrounded by a dashed frame 3020corresponds to a driving TFT which supplies a current to a lightemitting element 3021 directly or through other circuit elements. Thedriving TFT 3020 in FIG. 3B has an LDD region. The light emittingelement 3021 corresponds to a region in which a pixel electrode 3022,the electroluminescent layer 3001, and the counter electrode 3002 arelaminated and emits light in a direction shown by a light emittingdirection 3024. The pixel electrode 3022 is formed of a transparentconductive film and a film formed below the pixel electrode 3022 and thesubstrate 3000 are formed of materials which transmit light. Further, areflecting film 3005 is formed on the protective film 3004 and reflectslight emitted from the light emitting element 3021 in the oppositedirection to the light emitting direction 3024. Reference numeral 3003denotes an organic resin film.

[0049] The protective film 3004 is the same layer in FIG. 3A and FIG.3B, however, it may be formed of a different material.

[0050] The electroluminescent layer 3001 is the same layer in FIG. 3Aand FIG. 3B, however, it may be formed of a different material. Theelectroluminescent layers may be formed of different materials in eachpixel.

[0051] The color filter 3006 may be formed of a different material ineach pixel.

[0052] Further, the electroluminescent layer 3001 may be formed of anyof a low molecular weight material, a high molecular weight material, ora medium molecular weight material.

[0053] After the light emitting device is completed up to the mode shownin FIG. 3, it is preferably packaged (sealed) with a protective film(laminate film, ultraviolet curing resin film and the like) which hashigh airtightness and less degasification or a translucent coveringmaterial in order not to expose it to the outside air.

EMBODIMENT MODE 4

[0054] One embodiment mode of the invention is shown in FIG. 4. FIG. 4are cross sectional views of a first pixel portion and a second pixelportion of one light emitting device provided with two pixel portions.The first pixel portion has a structure to emit light only from acounter electrode side of the light emitting element while the secondpixel portion has a structure to emit light only from a pixel electrodeside of the light emitting element. That is, in the first pixel portionand the second pixel portion, directions of light emission are reversein front and back.

[0055]FIG. 4A is a cross sectional view of one pixel in the first pixelportion and FIG. 4B is a cross sectional view of one pixel in the secondpixel portion. FIG. 5 shows a circuit diagram of one pixel in the firstpixel portion and the second pixel portion as an example.

[0056] Note that a thin film transistor (TFT) is used as a switchingelement and a driving element here, however, the invention is notlimited to this. For example, any of a MOS transistor, an organictransistor, a molecular transistor and the like may be used as well.

[0057] In FIG. 5, reference numeral 900 denotes a pixel, 901 denotes aswitching TFT, 902 denotes a driving TFT, and 903 denotes a lightemitting element. Further, a symbol A denotes an anode line, C denotes acathode line, G denotes a gate line, and S denotes a source line.

[0058] In FIG. 4A, reference numeral 4000 denotes a substrate and aregion surrounded by a dashed frame 4010 corresponds to a driving TFTwhich supplies a current to a light emitting element 4011 directly orthrough other circuit elements. The light emitting element 4011corresponds to a region in which a pixel electrode 4012, anelectroluminescent layer 4001, and a counter electrode 4002 arelaminated and emits light in a direction shown by a light emittingdirection 4014. The pixel electrode 4012 at this time is formed of atransparent conductive film, however, light is not emitted from thebottom of the substrate 4000 even when the light is emitted in theopposite direction to the light emitting direction 4014 since the lightis reflected on the reflecting film 4015. The counter electrode 4002laminated above the electroluminescent layer 4001 is formed of atransparent conductive film while a protective film 4004 is formed of atransmissive film such as a carbon nitride film. Reference numeral 4003denotes an organic resin film.

[0059] In FIG. 4B, a region surrounded by a dashed frame 4020corresponds to a driving TFT which supplies a current to a lightemitting element 4021 directly or through other circuit elements. Thelight emitting element 4021 corresponds to a region in which a pixelelectrode 4022, the electroluminescent layer 4001, and the counterelectrode 4002 are laminated and emits light in a direction shown by alight emitting direction 4024. The pixel electrode 4022 is formed of atransparent conductive film and a film formed below the pixel electrode4022 and the substrate 4000 are formed of materials which transmitlight. Further, a reflecting film 4025 is formed on the protective film4004 and reflects light emitted from the light emitting element 4021 inthe opposite direction to the light emitting direction 4024. Referencenumeral 4003 denotes an organic resin film.

[0060] The electroluminescent layer 4001 is the same layer in FIG. 4Aand FIG. 4B, however, it may be formed of a different material. Theelectroluminescent layers may be formed of different materials in eachpixel.

[0061] The protective film 4004 is the same layer in FIG. 4A and FIG.4B, however, it may be formed of a different material.

[0062] Further, the electroluminescent layer 4001 may be formed of anyof a low molecular weight material, a high molecular weight material, ora medium molecular weight material.

[0063] After the light emitting device is completed up to the mode shownin FIG. 4, it is preferably packaged (sealed) with a protective film(laminate film, ultraviolet curing resin film and the like) which hashigh airtightness and less degasification or a translucent coveringmaterial in order not to expose it to the outside air.

EMBODIMENT

[0064] Hereinafter described is an embodiment of the invention.

EMBODIMENT 1

[0065] A panel substrate as a part of the light emitting device of theinvention is described.

[0066]FIG. 6A is a top plan view of a panel substrate with a substrate6000 on the bottom and a counter substrate 6002 on the top. FIG. 6B is across sectional view of the panel substrate. The substrate 6000 mounts afirst pixel portion 6010 and a second pixel portion 6020 at a differentdisposition than the first pixel portion 6010. The first pixel portion6010 emits light in a direction 6013 while the second pixel portion 6020emits light in a direction 6023, which are reverse in front and back.

[0067] A plurality of first pixels are arranged in matrix on the firstpixel portion 6010 and a plurality of second pixels are arranged inmatrix on the second pixel portion 6020. Each structure of the firstpixel and the second pixel is described in Embodiment Modes 1 to 4.

[0068] A space surrounded with a surface of the substrate 6000, asealing material 6001, and the counter substrate 6002 is sealed by afiller material except for a portion attached with an FPC 6003.

[0069] The first pixel portion 6010 is connected to a source signal linedriver circuit 6011 and gate signal line driver circuits 6012 a and 6012b, which supply signals required for the first pixel portion 6010 toemit light

[0070] The second pixel portion 6020 is connected to a source signalline driver circuit 6021, and gate signal line driver circuits 6022 aand 6022 b, which supply signals required for the second pixel portion6020 to emit light.

[0071] In this embodiment, in order to operate the first pixel portion6010 and the second pixel portion 6020, a source signal line drivercircuit and a gate signal line driver circuit are provided for each ofthem. However, a common source signal line driver circuit and a commongate signal line driver circuit for the first pixel portion 6010 and thesecond pixel portion 6020 may be provided as well.

[0072] The panel substrate is supplied with a signal and avoltage/current required for driving the source signal line drivercircuits 6011 and 6021, and the gate signal line driver circuits 6012 a,6012 b, 6022 a, and 6022 b through the FPC 6003. As for wirings forsupplying a signal and a voltage/current to the first pixel portion6010, the second pixel portion 6020, the source signal line drivercircuits 6011 and 6021, and the gate line driver circuits 6012 a, 6012b, 6022 a, and 6022 b, the number thereof can be reduced by sharing themas required. Here, a wiring for supplying a signal to a driver circuitis referred to as a signal line while a wiring for supplying a voltageto a driver circuit is referred to as a power supply line.

[0073] A signal and a voltage/current required to drive the sourcesignal line driver circuit 6011 and the gate signal line driver circuits6012 a and 6012 b are only required to be supplied when operating thefirst pixel portion 6010 while a signal and a voltage/current requiredto drive the source signal line driver circuit 6021 and the gate signalline driver circuits 6022 a and 6022 b are only required to be suppliedwhen operating the second pixel portion 6020.

[0074] In a structure that the first pixel portion 6010 and the secondpixel portion 6020 do not operate at the same time, they may be changedover externally by sharing a part or all of the wirings for supplying asignal and a voltage to the source signal line driver circuit 6011 foroperating the first pixel portion and the source signal line drivercircuit 6021 for operating the second pixel portion and providing ameans for operating either of the first pixel portion or the secondpixel portion. Further, they may be changed over externally by sharing apart or all of the wirings for supplying a signal and a voltage to thegate signal line driver circuits 6012 a and 6012 b for operating thefirst pixel portion and the gate signal line driver circuits 6022 a and6022 b for operating the second pixel portion and providing a means foroperating either of the first pixel portion or the second pixel portion.

[0075] In a structure that a part of an image to be displayed in thefirst pixel portion 6010 is displayed in the second pixel portion 6020,a wiring for supplying a video signal may be shared by the source signalline driver circuit 6011 and the source signal line driver circuit 6021.

[0076]FIG. 7 is an example of using the panel substrate to an electronicapparatus, for example a flip phone.

[0077] The flip phone in FIG. 7 is formed of a first housing 6100 and asecond housing 6200.

[0078] The first housing 6100 comprises a speaker 6101, a displaycontroller 6102, and the panel substrate of the invention. Note that6000 denotes a substrate and 6002 denotes a counter substrate.

[0079] The second housing 6200 comprises an antenna 6201, a microphone6202, a module 6203 for driving a main body, an operating button module6204, and a battery 6205.

[0080]FIG. 7A shows an opened flip phone. A user can look at an imagedisplayed in the first pixel portion 6010.

[0081]FIG. 7B shows a closed flip phone. A user can look at an imagedisplayed in the second pixel portion 6020. At this time, the usercannot look at the first pixel portion 6010, therefore, the first pixelportion 6010 is not required to display an image.

[0082]FIG. 7C shows a cross sectional view of the opened flip phone. Thefirst pixel portion 6010 emits light in a direction 6013 while thesecond pixel portion emits light in a direction 6023.

1. A light emitting device comprising: a first pixel portion in which aplurality of first pixels are arranged in matrix over a substrate; and asecond pixel portion in which a plurality of second pixels are arrangedin matrix at a different disposition than the first pixel portion overthe substrate, wherein each of the plurality of first pixels comprises afirst light emitting element; wherein each of the plurality of secondpixels comprises a second light emitting element; and wherein directionsof light emission of the first light emitting element and the secondlight emitting element are reverse in front and back.
 2. The lightemitting device according to claim 1, wherein the first light emittingelement comprises a first pixel electrode, a first electroluminescentlayer, and a first counter electrode; wherein the first pixel portionemits light from a side of the first counter electrode; wherein thesecond light emitting element comprises a second pixel electrode, asecond electroluminescent layer, and a second counter electrode; andwherein the second pixel portion emits light from a side of the secondpixel electrode.
 3. The light emitting device according to claim 1,wherein the directions of light emission of the first light emittingelement and the second light emitting element are determined dependingupon the presence or absence of a reflecting film.
 4. The light emittingdevice according to claim 1, wherein a first driving portion foroperating the first pixel portion, a second driving portion foroperating the second pixel portion, and a part or all of wirings forsupplying a signal and a voltage to each of the first driving portionand the second driving portion is shared; and wherein a means foroperating either of the first pixel portion or the second pixel portionis provided.
 5. An electronic apparatus using the light emitting deviceaccording to claim
 1. 6. A portable phone using the light emittingdevice according to claim
 1. 7. A personal digital assistance (PDA)using the light emitting device according to claim
 1. 8. A lightemitting device comprising: a first pixel portion in which a pluralityof first pixels are arranged in matrix over a substrate; and a secondpixel portion in which a plurality of second pixels are arranged inmatrix at a different disposition than the first pixel portion over thesubstrate, wherein each of the plurality of first pixels comprises afirst light emitting element which emits light from a surface of thesubstrate in a direction from a back of the substrate to the surface ofthe substrate; and wherein each of the plurality of second pixelscomprises a second light emitting element which emits light from theback of the substrate in a direction from the surface of the substrateto the back of the substrate.
 9. The light emitting device according toclaim 8, wherein the first light emitting element comprises a firstpixel electrode, a first electroluminescent layer, and a first counterelectrode; wherein the first pixel portion emits light from a side ofthe first counter electrode; wherein the second light emitting elementcomprises a second pixel electrode, a second electroluminescent layer,and a second counter electrode; and wherein the second pixel portionemits light from a side of the second pixel electrode.
 10. The lightemitting device according to claim 8, wherein the directions of lightemission of the first light emitting element and the second lightemitting element are determined depending upon the presence or absenceof a reflecting film.
 11. The light emitting device according to claim8, wherein a first driving portion for operating the first pixelportion, a second driving portion for operating the second pixelportion, and a part or all of wirings for supplying a signal and avoltage to each of the first driving portion and the second drivingportion is shared; and wherein a means for operating either of the firstpixel portion or the second pixel portion is provided.
 12. An electronicapparatus using the light emitting device according to claim
 8. 13. Aportable phone using the light emitting device according to claim
 8. 14.A personal digital assistance (PDA) using the light emitting deviceaccording to claim 8.